Interventions to reduce contaminated aerosols produced during dental procedures for preventing infectious diseases.

BACKGROUND: Many dental procedures produce aerosols (droplets, droplet nuclei and splatter) that harbour various pathogenic micro-organisms and may pose a risk for the spread of infections between dentist and patient. The COVID-19 pandemic has led to greater concern about this risk. OBJECTIVES: To assess the effectiveness of methods used during dental treatment procedures to minimize aerosol production and reduce or neutralize contamination in aerosols. SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the following databases on 17 September 2020: Cochrane Oral Health's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (in the Cochrane Library, 2020, Issue 8), MEDLINE Ovid (from 1946); Embase Ovid (from 1980); the WHO COVID-19 Global literature on coronavirus disease; the US National Institutes of Health Trials Registry (ClinicalTrials.gov); and the Cochrane COVID-19 Study Register. We placed no restrictions on the language or date of publication. SELECTION CRITERIA: We included randomized controlled trials (RCTs) and controlled clinical trials (CCTs) on aerosol-generating procedures (AGPs) performed by dental healthcare providers that evaluated methods to reduce contaminated aerosols in dental clinics (excluding preprocedural mouthrinses). The primary outcomes were incidence of infection in dental staff or patients, and reduction in volume and level of contaminated aerosols in the operative environment. The secondary outcomes were cost, accessibility and feasibility. DATA COLLECTION AND ANALYSIS: Two review authors screened search results, extracted data from the included studies, assessed the risk of bias in the studies, and judged the certainty of the available evidence. We used mean differences (MDs) and 95% confidence intervals (CIs) as the effect estimate for continuous outcomes, and random-effects meta-analysis to combine data. We assessed heterogeneity. MAIN RESULTS: We included 16 studies with 425 participants aged 5 to 69 years. Eight studies had high risk of bias; eight had unclear risk of bias. No studies measured infection. All studies measured bacterial contamination using the surrogate outcome of colony-forming units (CFU). Two studies measured contamination per volume of air sampled at different distances from the patient's mouth, and 14 studies sampled particles on agar plates at specific distances from the patient's mouth. The results presented below should be interpreted with caution as the evidence is very low certainty due to heterogeneity, risk of bias, small sample sizes and wide confidence intervals. Moreover, we do not know the 'minimal clinically important difference' in CFU. High-volume evacuator Use of a high-volume evacuator (HVE) may reduce bacterial contamination in aerosols less than one foot (~ 30 cm) from a patient's mouth (MD -47.41, 95% CI -92.76 to -2.06; 3 RCTs, 122 participants (two studies had split-mouth design); very high heterogeneity I² = 95%), but not at longer distances (MD -1.00, -2.56 to 0.56; 1 RCT, 80 participants). One split-mouth RCT (six participants) found that HVE may not be more effective than conventional dental suction (saliva ejector or low-volume evacuator) at 40 cm (MD CFU -2.30, 95% CI -5.32 to 0.72) or 150 cm (MD -2.20, 95% CI -14.01 to 9.61). Dental isolation combination system One RCT (50 participants) found that there may be no difference in CFU between a combination system (Isolite) and a saliva ejector (low-volume evacuator) during AGPs (MD -0.31, 95% CI -0.82 to 0.20) or after AGPs (MD -0.35, -0.99 to 0.29). However, an 'n of 1' design study showed that the combination system may reduce CFU compared with rubber dam plus HVE (MD -125.20, 95% CI -174.02 to -76.38) or HVE (MD -109.30, 95% CI -153.01 to -65.59). Rubber dam One split-mouth RCT (10 participants) receiving dental treatment, found that there may be a reduction in CFU with rubber dam at one-metre (MD -16.20, 95% CI -19.36 to -13.04) and two-metre distance (MD -11.70, 95% CI -15.82 to -7.58). One RCT of 47 dental students found use of rubber dam may make no difference in CFU at the forehead (MD 0.98, 95% CI -0.73 to 2.70) and occipital region of the operator (MD 0.77, 95% CI -0.46 to 2.00). One split-mouth RCT (21 participants) found that rubber dam plus HVE may reduce CFU more than cotton roll plus HVE on the patient's chest (MD -251.00, 95% CI -267.95 to -234.05) and dental unit light (MD -12.70, 95% CI -12.85 to -12.55). Air cleaning systems One split-mouth CCT (two participants) used a local stand-alone air cleaning system (ACS), which may reduce aerosol contamination during cavity preparation (MD -66.70 CFU, 95% CI -120.15 to -13.25 per cubic metre) or ultrasonic scaling (MD -32.40, 95% CI - 51.55 to -13.25). Another CCT (50 participants) found that laminar flow in the dental clinic combined with a HEPA filter may reduce contamination approximately 76 cm from the floor (MD -483.56 CFU, 95% CI -550.02 to -417.10 per cubic feet per minute per patient) and 20 cm to 30 cm from the patient's mouth (MD -319.14 CFU, 95% CI - 385.60 to -252.68). Disinfectants ‒ antimicrobial coolants Two RCTs evaluated use of antimicrobial coolants during ultrasonic scaling. Compared with distilled water, coolant containing chlorhexidine (CHX), cinnamon extract coolant or povidone iodine may reduce CFU: CHX (MD -124.00, 95% CI -135.78 to -112.22; 20 participants), povidone iodine (MD -656.45, 95% CI -672.74 to -640.16; 40 participants), cinnamon (MD -644.55, 95% CI -668.70 to -620.40; 40 participants). CHX coolant may reduce CFU more than povidone iodine (MD -59.30, 95% CI -64.16 to -54.44; 20 participants), but not more than cinnamon extract (MD -11.90, 95% CI -35.88 to 12.08; 40 participants). AUTHORS' CONCLUSIONS: We found no studies that evaluated disease transmission via aerosols in a dental setting; and no evidence about viral contamination in aerosols. All of the included studies measured bacterial contamination using colony-forming units. There appeared to be some benefit from the interventions evaluated but the available evidence is very low certainty so we are unable to draw reliable conclusions. We did not find any studies on methods such as ventilation, ionization, ozonisation, UV light and fogging. Studies are needed that measure contamination in aerosols, size distribution of aerosols and infection transmission risk for respiratory diseases such as COVID-19 in dental patients and staff.

Cleaning of used rotary nickel-titanium files in an ultrasonic bath by locally intensified acoustic cavitation.

AIM: To compare the pre-sterilization cleaning of rotary Ni-Ti files of different sizes previously used a. ex vivo and b. clinically by a washer-disinfector, a regular ultrasonic bath, and the same ultrasonic bath in combination with a recently developed cavitation intensifying method. METHODOLOGY: Two sets of two hundred rotary Ni-Ti files, one previously used ex vivo and another one used clinically, were collected from the undergraduate and postgraduate clinics of the Academic Centre for Dentistry Amsterdam (ACTA). The instruments were immersed in an enzymatic solution and subsequently cleaned either by a washer-disinfector, a regular ultrasonic bath combined with a glass beaker, the same bath combined with a beaker lined with two cavitation intensifying sheets or with two standard plastic sheets. The positive control consisted of used files that did not undergo any cleaning and the negative control included new unused files. The instruments were then stained to reveal remaining protein material and scored under a stereoscopic microscope. The results were analysed by nonparametric statistical tests (α = 0.05). RESULTS: No significant difference was found between the combination of the ultrasonic bath and the regular glass beaker and the same ultrasonic bath with the beaker lined with the cavitation intensifying sheets. The washer-disinfector left significantly more debris compared to the latter group when clinically used files were evaluated (P ≤ 0.001). The effect of instrument size on cleaning was not consistent. CONCLUSION: None of the tested methods was able to remove all residual protein material from the files; however, it could be noted that this study did not follow the reprocessing protocol provided by the manufacturer.

Sterilization for Large Volunteer Temporary Clinics.

Large portable clinics staffed by volunteers present many unique challenges, including establishing appropriate instrument processing services. This article explores many of the specific steps an organization can take to ensure a safe care environment for patients and a safe working environment for volunteers.

Infection control in digital intraoral radiography: evaluation of microbiological contamination of photostimulable phosphor plates in barrier envelopes.

BACKGROUND AND OBJECTIVE: The detectors (both solid-state sensors and photostimulable phosphor [PSP] plates) used for digital intraoral radiography cannot be autoclaved, and barriers are typically used to prevent the spread of infection. The aim of this study was to determine the effectiveness of a barrier envelope system for PSP plates. METHODS: Disinfected PSP plates were aseptically inserted into barrier envelopes and placed in a periapical location. One PSP plate was placed in each of 28 patients, and 12 plates in each of 2 volunteers (D.S.M., J.D.W.). After retrieval, each PSP plate was removed from its barrier envelope, immersed in trypticase soy broth and aliquots were plated on trypticase soy agar. Bacterial colonies were counted 2 days later. RESULTS: Fifty-two PSP plates in barrier envelopes were evaluated for contamination. Quality assurance of the PSP plates before clinical placement revealed defects in the integrity of 4 barrier envelopes, caused by forceps-related damage or failure to achieve a uniform seal. These defects allowed substantial contamination. Contamination also occurred as a result of failure to extract the PSP plate from the barrier envelope cleanly. Of the 44 barriers with no obvious defects that were placed by either final-year dental students or a radiologist, only 3 allowed bacterial contamination of the PSP plate. CONCLUSION: Detectors contained in barrier envelopes remain a potential source of contamination. PSP plates must be disinfected between removal from a contaminated barrier envelope and placement in a new barrier envelope. In addition, placement into the barrier envelope should ideally be carried out under aseptic conditions. Finally, the integrity of each sealed barrier envelope must be verified visually before release to the clinic.

Improving the provision of the Basic Package of Oral Care (BPOC) in Cambodia.

UNLABELLED: Since 1992, 330 medical nurses have been trained to provide basic oral health care (including ART restorations and dental extractions) in remote areas of Cambodia. However, a range of barriers prevent dental nurses from providing these services, especially a lack of dental materials and instruments. OBJECTIVES: To increase dental nurse (DN) outputs through the regular provision of dental materials and instruments. To improve cross-infection control procedures through the provision of necessary equipment, supplies and training. METHODS: Six health centres with active DNs participated; three (experimental) health centres received sufficient supplies of dental instruments and materials for one year, and 3-monthly visits by a dentist from the Ministry of Health. The other three health centres (control) did not. RESULTS: During the project period, the experimental group extractions increased to an average of 119 extractions per quarter (a three-fold increase compared to the baseline), 51 ART restorations, and improved compliance with cross-infection infection control protocols. In the control group the number of extractions remained similar to baseline and no ART restorations were placed. CONCLUSIONS: The provision of the BPOC increased in the health centres when sufficient supplies of dental materials and instruments were provided. Increased monitoring and communication with MOH dental colleagues was also associated with the increased outputs and resulted in improved compliance with cross-infection control protocols. The MOH should increase supplies to DNs and provide ongoing monitoring and support in order to improve the access to and quality of dental care provided in rural Cambodia.

Reducing Staphylococcus aureus bacterial counts in a dental clinic using an Ionic Breeze air purifier: a preliminary study.

Aerosols and droplets generated by dental procedures are contaminated with blood and bacteria and represent a potential route for the transmission of disease. This study sought to determine if Ionic Breeze air purifiers are effective in collecting and destroying bacteria found in dental aerosols (such as Staphylococcus aureus). This study placed one Sharper Image Professional Series Ionic Breeze Quadra unit and one Ionic Breeze GP unit (with germicidal protection) in dental operatories within the Louisiana State University School of Dentistry. After six hours of operation, bacterial samples were collected and streaked over surfaces of petri dishes containing trypticase soy sucrose bacitracin agar that had been supplemented with 5% sheep blood. The samples were incubated at 37 degrees C for 48 hours; at that point, the microbial colonies were counted. Additional testing was performed on suspect colonies to identify S. aureus strains and to determine if any of those isolates were pathogenic with or without antibiotic resistance. The Ionic Breeze GP unit killed more than 99% of all bacteria on the stainless steel collecting blades. The non-germicidal Ionic Breeze Quadra air purifier collected numerous bacteria that were found to include some pathogenic strains of S. aureus; however, none of these were resistant to antibiotics.

Clinical usefulness of "Isolite Plus" for oral environment of Japanese people.

The recent demand for dental devices which are easier to handle and offer higher levels of reliability and safety has led to the development in the US of Isolite Plus, a new oral support device. When placed in the oral cavity, Isolite Plus enables marking of the surgical field, secures the treatment space, ensures a vacuum, protects the cheek and tongue, assists in opening the mouth, prevents accidental ingestion/aspiration, ensures treatment without contamination and enhances comfort and safety during dental treatment. The present study was carried out to verify whether Isolite Plus can fit well in the mouth of Japanese people and to determine whether it performs adequately. Thirty resident dentists were required to wear Isolite Plus in their mouth and perform mutual simulation training using an air turbine handpiece. After the training, both subjects playing the role of surgeon and those playing the role of patient were asked to complete questionnaires. On the basis of the results, we discuss the clinical usefulness of Isolite Plus in Japanese people. In the present investigation, Isolite Plus was rated slightly better by surgeons than by patients. The supportive functions of the device were judged inadequate due to the poor fit of the mouthpiece portion of the device to subjects' mouth. For the distribution of Isolite Plus in the Japanese market, the mouthpiece portion of the device should be improved so that it can fit the mouth of Japanese people.

[Conditions of dental extractions in areas health centers of Senegal]. / Etude des conditions de l'extraction dentaire dans les centres de santé des districts du Sénégal.

Dental extraction is a surgical act frequently carried out in the African dental structures. It requires the rigorous respect of the conditions of asepsis and antisepsis. Equipments and anaesthetic and avulsional products must be also sufficient. Our study undertaken among 46 dental services in areas health centers of Senegal aimed to determine the conditions under which dental extractions are carried out. The principle results of our study showed that 93% of dental practitioners wore sterilized gloves. 49% of the dentist's care activity consisted in dental extractions. 50% of the practitioners re-use anaesthetic needles, 2% re-use anaesthetic carpules. We noticed that the dental structures were facing a deficit of materials and products of extraction. Face to the outbreak of serious illnesses as infections of HIV and Hepatitis B, the practitioner and his team must be sensitized and trained to struggle against the transmissible infections and to carry out the dental extraction only if the conditions of asepsis and antisepsis are joined together. A pleading towards the medical authorities must be done to support the services in equipments and periodic renewals of the materials and products of extractions.

[The effectiveness of glass bead sterilizer in the dental practice].

OBJECTIVES: Although it is not FDA-approved as inter-patients sterilization measure, in Israel, glass bead sterilizer is still a common method for chair-side sterilization of small dental hand instruments, especially endodontic files. Studies from the 1950-1970s achieved sterilization by the bead sterilizer within few seconds. Nevertheless, there are no current evidence-based instructions for using this sterilizer. The study was designed to evaluate the effectiveness of this method in sterilization of endodontic files, according to current microbiologic knowledge. METHODS: Standard endodontic k-files (#15, 50, 80) were sterilized in a steam autoclave and then soaked in Actinomyces israelii, Eikenella corrodens or Bacillus cereus [0.5 MacFarland] media for 10 sec. After drying, the files were placed in 225 degrees C or 250 degrees C-heated glass bead sterilizers for 0, 15, 30 or 60 sec. After appropriate incubation for 10 d, morphologic and biochemical examinations were performed to reveal bacterial growth. RESULTS: Files that have been contaminated with A. israelii were sterilized within 30 sec, whereas B. cereus and E. corrodens-contaminated files needed 60 sec for sterilization. CONCLUSIONS: The use in bead sterilizer has to be limited only for sterilization of intra-appointment purpose. However, it seems that the common method of using bead sterilizer for sterilization time of few seconds is not effective. In order to eliminate spore-forming bacteria, like B. cereus, by bead sterilizer, the sterilization time has to be at least 60 sec. More research is needed, however, for establishing the effectiveness of the bead sterilizer for viral infection control and for other dental instruments.

[Efficacy of the pasteur oven as sterilization equipment in dental offices]. / Eficácia da estufa de Pasteur como equipamento esterilizante em consultórios odontológicos.

This study was aimed at assessing the efficacy of the use of the Pasteur oven as sterilization equipment in dental offices through biological monitoring. For this assessment were taken into account how adequately the material is loaded into the equipment; time/temperature used; and preventive maintenance of the oven. The data were collected in 101 dental offices in the Central District of GoiPnia, in the State of Goiás, through observation, interviews and performance of tests with biological indicator. The results showed a lack of standardization of some of the procedures recommended by the Ministry of Health for sterilization of items in the oven, and positive results of the biological test in 46 (45.5%) of the tested cycles. The intervening factors with most significance regarding sterilization problems were: absence of an accessory thermometer to control the cycles' temperature and non-observance of the time/temperature relations recommended for the sterilization cycle through dry heat.

A pilot study of the effects of a vacuum sealing barrier method for photostimulable phosphor plates regarding plate damage and prevention of microbiologic cross-contamination.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of a new sealing method for preventing cross-contamination of photostimulable phosphor (PSP) plates. STUDY DESIGN: Twelve new PSP plates were divided into 3 groups (PSP-a, PSP-b, and PSP- c) and placed in 3 different barriers (2 different brands of envelopes and a vacuum sealing method). All plates were exposed to X-rays with an aluminum step wedge, and the images were evaluated for the presence of any artifacts. After radiography, the PSP plates were removed from the barriers. The barriers and the PSP plates were disinfected and culture performed to assess any microorganism burden. Subsequently, the PSP plates were coated again with all barriers. The barriers were then contaminated and microbiologic specimens were collected. Subsequently, the barriers were wiped with alcohol. The PSP plates were removed, and microbiologic specimens were obtained. RESULTS: No artifacts were recorded on the radiographic images on the sensors in any group. Microorganisms were detected on the PSP plates placed in envelopes. No colonization of microorganisms was detected on the vacuum sealed PSP plates. CONCLUSIONS: The new vacuum-sealing method may be useful in preventing cross-contamination of PSP plates during radiographic procedures.

Comparison of an ultrasonic cleaner and a washer disinfector in the cleaning of endodontic files.

The aim of this study was to compare the amount of residual organic debris on endodontic instruments that had been cleaned in either an ultrasonic bath or a washer disinfector prior to sterilisation. A total of 90 endodontic files of varying sizes were used to clean and shape root canals in extracted teeth and were then placed in endodontic file holders. Test group 1 (36 files) were ultrasonically cleaned for 10 min and test group 2 (36 files) were cleaned in a washer disinfector. A control group (18 files) were not cleaned at all. Following sterilisation, all the files were visually inspected under a light microscope and scored using an established scale. The results showed that both test groups had significantly less residual debris than the control group. Comparing the test groups, the files that had been cleaned ultrasonically had significantly less debris than those cleaned in the washer disinfector. The design of the instrument holder may have been a factor in this result. More research is needed into the use of washer disinfectors in the cleaning of small dental instruments that have a complex surface structure.

Dental bioaerosol as an occupational hazard in a dentist's workplace.

Many-year studies on aerosols as an infection vector, despite their wide range, ignored dental aerosol. All procedures performed with the use of dental unit handpieces cause the formation of aerosol and splatter which are commonly contaminated with bacteria, viruses, fungi, often also with blood. Aerosols are liquid and solid particles, 50 microm or less in diameter, suspended in air. Splatter is usually described as a mixture of air, water and/or solid substances; water droplets in splatter are from 50 microm to several millimetres in diameter and are visible to the naked eye. The most intensive aerosol and splatter emission occurs during the work of an ultrasonic scaler tip and a bur on a high-speed handpiece. Air-water aerosol produced during dental treatment procedures emerges from a patient's mouth and mixes with the surrounding air, thus influencing its composition. Because air contained in this space is the air breathed by both dentist and patient, its composition is extremely important as a potential threat to the dentist's health. According to the author, insufficient awareness of health risk, working habits, and economic factors are the reasons why dentists do not apply the available and recommended methods of protection against the influence of bioaerosol and splatter. Behaviour protecting a dentist and an assistant from the threat resulting from the influence of dental aerosol cannot be limited to isolated actions. The author, on the basis of the literature and own research, characterizes bioaerosol and splatter in a dental surgery and reviews a full range of protective measures against these risk factors.

Knowledge of and attitudes toward severe acute respiratory syndrome among a cohort of dental patients in Hong Kong following a major local outbreak.

OBJECTIVE: To assess the knowledge of and attitudes toward severe acute respiratory syndrome (SARS) among patients attending a teaching dental hospital and private dental practices in Hong Kong during a major local SARS outbreak. METHODS: 250 dental patients were interviewed by questionnaire and 213 were interviewed by phone. RESULTS: Less than one-third (30.0%) of the 463 respondents said they were not afraid of contracting the SARS coronavirus from their dentists and did not avoid dental treatment for that reason. Nearly three-fifths (56.7%) did not worry about contracting SARS from dental treatment. Fewer than 10% of the respondents thought that dentists ran a high risk of contracting SARS. From the patients' experiences, 85.2% and 21.7% of the dentists wore face masks and face shields, respectively, when delivering dental treatment. CONCLUSIONS: The majority of patients interviewed had confidence in their dentists, their treatment environments, and the infection control measures taken, and were not worried about contracting SARS in the dental setting. This perception is an improvement from that described in an earlier study, in which more than half of the patients were concerned about contracting an infection during dental treatment and perceived that the infection control measures undertaken by the dental profession to prevent infectious diseases were not satisfactory. Patients, however, demanded better infection control measures during the SARS outbreak.

Infection control: a survey of UK special care dentists and dental care professionals.

AIM: To determine attitudes to and practice of infection control among practitioners involved in special care dentistry. METHODS: A questionnaire on the issues of decontamination and infection control was sent to all 680 members of the British Society for Disability and Oral Health. RESULTS: The response rate was 63.5%. Almost all respondents (95%) reported having a local infection-control policy; most (97%) had local protocols for the management of inoculation injuries; most (81%) gave new staff training in infection-control procedures and most (74%) provided updates for established staff. Most respondents 'usually' or 'always' provided eye protection for patients (95%) and themselves (93%). Virtually all routinely wore gloves, and nearly all (94%) 'always' changed gloves between patients. The majority 'usually' or 'always' disinfected or disposed of surface coverings between patients (98%), sterilised all non-disposable instruments that had been set out for the patient (99%), and disinfected laboratory work (96%). CONCLUSIONS: There was high awareness of infection-control issues, and good reported compliance among these dental workers.

Instrument cassettes for office safety and infection control.

The goal of a dental infection control program is to provide a safe working environment that will reduce the risk of health care-associated infections among patients and occupational exposures among staff members. Minimizing the potential for percutaneous sharps injuries is a primary focus for a comprehensive infection control program. This article will review the advantages of using instrument cassettes, as well as provide an overview of engineering and work practice controls and instrument processing, to emphasize how appropriate use of instrument cassettes can improve office safety and infection control.

Dental dams: the secret tool for infection control.

Dental dams, although in existence for over 100 years, are the most widely underused tool of infection control. This article addresses the many benefits of using dental dams and discusses simplified methods of incorporating dams into the dental practice.